This invention was made with Government support. The Government has certain rights in this invention.
The present invention relates generally to an electrically small aperture antenna with field minimization capabilities, and more particularly to a satellite antenna system wherein protected devices may be placed at the null location created by the field minimized antenna.
Satellite technology has long dictated that advancements in performance, function, and capabilities must be balanced by size and weight restrictions. This need to integrate form and function has led to a variety of advancements and continues to spur the development of further advancements. One subfield of satellite technology driven by such design characteristics has been the subfield of satellite antennae design. Multiple antennae arrays must often be utilized on a single satellite assembly in order to provide desired functionality. Size and weight restrictions on the satellite assembly often dictate that the multiple antennae arrays must be positioned within close proximity to each other. Design complications arise, however, when the proximity of such satellite arrays causes interference between individual antennae arrays and other field sensitive units within the satellite system.
One approach towards limiting the effect of an antennae array on surrounding components has been through the use of RF chokes. RF chokes are commonly corrugations around the perimeter of the antennae aperture utilized to suppress currents from promulgating past the aperture bore sight axis. The RF chokes are commonly used to suppress side lobes by reducing the current on the backside of the antennae aperture flanges. The depth of the RF choke is commonly set near a quarter wavelength deep and the amount of side lobe reduction is commonly limited by the allowable width of the choke. Although these known configurations can reduce in side lobe reduction, they leave considerable room for improvement in interference reduction between antennae arrays and other hardware.
Although present RF choke design is commonly configured to result in side lobe reduction, the current suppression provided by such designs commonly allow aperture fields to promulgate and cause interference with surrounding components. Sensors, receiving antennas, and imagers can all be negatively impacted by the aperture field promulgating from the antennae. Although overall reduction of the aperture field may be beneficial for the overall satellite design, specific components may require further field reduction as their mounting position on the satellite assembly. It would, therefore, be highly beneficial to have an antennae assembly whose design could be modified such that the aperture fields created by the antennae assembly could be minimized in locations where critical components are mounted. Since packaging requirements on the satellite system are often highly restrictive, such an antennae design would provide valuable placement freedom for such critical components.
Additionally, sizing, packaging, and weight restrictions inherent in satellite design dictate that a compact antennae design capable of minimizing the aperture field in locations of critical component placement would also be highly desirable.
It is, therefore, an object of the present invention to provide a satellite assembly including an aperture antennae configured to minimize the aperture field near a field sensitive component. It is a further object of the present invention to provide an aperture antennae with field minimization characteristics. The aperture antennae having a compact design.
In accordance with the objects of the present invention, a satellite assembly is provided. The satellite assembly includes an aperture antennae assembly including a plurality of RF choke elements. Each of the RF chokes is defined by an RF dimensional set which includes an RF width and an RF depth. The RF dimensional sets for each of the RF chokes are varied such that the plurality of RF choke elements create a null aperture field zone. The satellite assembly further includes at least one field sensitive component positioned in the null aperture field zone.